The BEGIN forces the require and import to happen at compile time. The require makes sure the module is loaded into memory if it hasn't been yet. The import is not a builtin--it's just an ordinary static method call into the ``Module'' package to tell the module to import the list of features back into the current package. The module can implement its import method any way it likes, though most modules just choose to derive their import method via inheritance from the Exporter class that is defined in the Exporter module. See Exporter.
If you don't want your namespace altered, explicitly supply an empty list:
That is exactly equivalent to
Because this is a wide-open interface, pragmas (compiler directives) are also implemented this way. Currently implemented pragmas are:
These pseudomodules import semantics into the current block scope, unlike ordinary modules, which import symbols into the current package (which are effective through the end of the file).
There's a corresponding ``no'' command that unimports meanings imported by use.
See the perlmod manpage for a list of standard modules and pragmas.